// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/sys_info.h"

#include <dlfcn.h>
#include <stddef.h>
#include <stdint.h>
#include <sys/system_properties.h>

#include "base/android/jni_android.h"
#include "base/android/sys_utils.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_piece.h"
#include "base/strings/stringprintf.h"
#include "base/sys_info_internal.h"

#if (__ANDROID_API__ >= 21 /* 5.0 - Lollipop */)

namespace {

typedef int(SystemPropertyGetFunction)(const char*, char*);

SystemPropertyGetFunction* DynamicallyLoadRealSystemPropertyGet()
{
    // libc.so should already be open, get a handle to it.
    void* handle = dlopen("libc.so", RTLD_NOLOAD);
    if (!handle) {
        LOG(FATAL) << "Cannot dlopen libc.so: " << dlerror();
    }
    SystemPropertyGetFunction* real_system_property_get = reinterpret_cast<SystemPropertyGetFunction*>(
        dlsym(handle, "__system_property_get"));
    if (!real_system_property_get) {
        LOG(FATAL) << "Cannot resolve __system_property_get(): " << dlerror();
    }
    return real_system_property_get;
}

static base::LazyInstance<base::internal::LazySysInfoValue<
    SystemPropertyGetFunction*, DynamicallyLoadRealSystemPropertyGet>>::Leaky
    g_lazy_real_system_property_get
    = LAZY_INSTANCE_INITIALIZER;

} // namespace

// Android 'L' removes __system_property_get from the NDK, however it is still
// a hidden symbol in libc. Until we remove all calls of __system_property_get
// from Chrome we work around this by defining a weak stub here, which uses
// dlsym to but ensures that Chrome uses the real system
// implementatation when loaded.  http://crbug.com/392191.
BASE_EXPORT int __system_property_get(const char* name, char* value)
{
    return g_lazy_real_system_property_get.Get().value()(name, value);
}

#endif

namespace {

// Default version of Android to fall back to when actual version numbers
// cannot be acquired. Use the latest Android release with a higher bug fix
// version to avoid unnecessarily comparison errors with the latest release.
// This should be manually kept up to date on each Android release.
const int kDefaultAndroidMajorVersion = 7;
const int kDefaultAndroidMinorVersion = 0;
const int kDefaultAndroidBugfixVersion = 99;

// Parse out the OS version numbers from the system properties.
void ParseOSVersionNumbers(const char* os_version_str,
    int32_t* major_version,
    int32_t* minor_version,
    int32_t* bugfix_version)
{
    if (os_version_str[0]) {
        // Try to parse out the version numbers from the string.
        int num_read = sscanf(os_version_str, "%d.%d.%d", major_version,
            minor_version, bugfix_version);

        if (num_read > 0) {
            // If we don't have a full set of version numbers, make the extras 0.
            if (num_read < 2)
                *minor_version = 0;
            if (num_read < 3)
                *bugfix_version = 0;
            return;
        }
    }

    // For some reason, we couldn't parse the version number string.
    *major_version = kDefaultAndroidMajorVersion;
    *minor_version = kDefaultAndroidMinorVersion;
    *bugfix_version = kDefaultAndroidBugfixVersion;
}

// Parses a system property (specified with unit 'k','m' or 'g').
// Returns a value in bytes.
// Returns -1 if the string could not be parsed.
int64_t ParseSystemPropertyBytes(const base::StringPiece& str)
{
    const int64_t KB = 1024;
    const int64_t MB = 1024 * KB;
    const int64_t GB = 1024 * MB;
    if (str.size() == 0u)
        return -1;
    int64_t unit_multiplier = 1;
    size_t length = str.size();
    if (str[length - 1] == 'k') {
        unit_multiplier = KB;
        length--;
    } else if (str[length - 1] == 'm') {
        unit_multiplier = MB;
        length--;
    } else if (str[length - 1] == 'g') {
        unit_multiplier = GB;
        length--;
    }
    int64_t result = 0;
    bool parsed = base::StringToInt64(str.substr(0, length), &result);
    bool negative = result <= 0;
    bool overflow = result >= std::numeric_limits<int64_t>::max() / unit_multiplier;
    if (!parsed || negative || overflow)
        return -1;
    return result * unit_multiplier;
}

int GetDalvikHeapSizeMB()
{
    char heap_size_str[PROP_VALUE_MAX];
    __system_property_get("dalvik.vm.heapsize", heap_size_str);
    // dalvik.vm.heapsize property is writable by a root user.
    // Clamp it to reasonable range as a sanity check,
    // a typical android device will never have less than 48MB.
    const int64_t MB = 1024 * 1024;
    int64_t result = ParseSystemPropertyBytes(heap_size_str);
    if (result == -1) {
        // We should consider not exposing these values if they are not reliable.
        LOG(ERROR) << "Can't parse dalvik.vm.heapsize: " << heap_size_str;
        result = base::SysInfo::AmountOfPhysicalMemoryMB() / 3;
    }
    result = std::min<int64_t>(std::max<int64_t>(32 * MB, result), 1024 * MB) / MB;
    return static_cast<int>(result);
}

int GetDalvikHeapGrowthLimitMB()
{
    char heap_size_str[PROP_VALUE_MAX];
    __system_property_get("dalvik.vm.heapgrowthlimit", heap_size_str);
    // dalvik.vm.heapgrowthlimit property is writable by a root user.
    // Clamp it to reasonable range as a sanity check,
    // a typical android device will never have less than 24MB.
    const int64_t MB = 1024 * 1024;
    int64_t result = ParseSystemPropertyBytes(heap_size_str);
    if (result == -1) {
        // We should consider not exposing these values if they are not reliable.
        LOG(ERROR) << "Can't parse dalvik.vm.heapgrowthlimit: " << heap_size_str;
        result = base::SysInfo::AmountOfPhysicalMemoryMB() / 6;
    }
    result = std::min<int64_t>(std::max<int64_t>(16 * MB, result), 512 * MB) / MB;
    return static_cast<int>(result);
}

} // anonymous namespace

namespace base {

std::string SysInfo::HardwareModelName()
{
    char device_model_str[PROP_VALUE_MAX];
    __system_property_get("ro.product.model", device_model_str);
    return std::string(device_model_str);
}

std::string SysInfo::OperatingSystemName()
{
    return "Android";
}

std::string SysInfo::OperatingSystemVersion()
{
    int32_t major, minor, bugfix;
    OperatingSystemVersionNumbers(&major, &minor, &bugfix);
    return StringPrintf("%d.%d.%d", major, minor, bugfix);
}

void SysInfo::OperatingSystemVersionNumbers(int32_t* major_version,
    int32_t* minor_version,
    int32_t* bugfix_version)
{
    // Read the version number string out from the properties.
    char os_version_str[PROP_VALUE_MAX];
    __system_property_get("ro.build.version.release", os_version_str);

    // Parse out the numbers.
    ParseOSVersionNumbers(os_version_str, major_version, minor_version,
        bugfix_version);
}

std::string SysInfo::GetAndroidBuildCodename()
{
    char os_version_codename_str[PROP_VALUE_MAX];
    __system_property_get("ro.build.version.codename", os_version_codename_str);
    return std::string(os_version_codename_str);
}

std::string SysInfo::GetAndroidBuildID()
{
    char os_build_id_str[PROP_VALUE_MAX];
    __system_property_get("ro.build.id", os_build_id_str);
    return std::string(os_build_id_str);
}

int SysInfo::DalvikHeapSizeMB()
{
    static int heap_size = GetDalvikHeapSizeMB();
    return heap_size;
}

int SysInfo::DalvikHeapGrowthLimitMB()
{
    static int heap_growth_limit = GetDalvikHeapGrowthLimitMB();
    return heap_growth_limit;
}

static base::LazyInstance<
    base::internal::LazySysInfoValue<bool,
        android::SysUtils::IsLowEndDeviceFromJni>>::Leaky
    g_lazy_low_end_device
    = LAZY_INSTANCE_INITIALIZER;

bool SysInfo::IsLowEndDevice()
{
    // This code might be used in some environments
    // which might not have a Java environment.
    // Note that we need to call the Java version here.
    // There exists a complete native implementation in
    // sys_info.cc but calling that here would mean that
    // the Java code and the native code would call different
    // implementations which could give different results.
    // Also the Java code cannot depend on the native code
    // since it might not be loaded yet.
    if (!base::android::IsVMInitialized())
        return false;
    return g_lazy_low_end_device.Get().value();
}

} // namespace base
